Automatic Wellbore Survey Evaluation

ABSTRACT

A method for automatically evaluating a survey of a subterranean wellbore includes receiving downhole navigation sensor measurements and automatically evaluating surface sensor data obtained at substantially the same time as the navigation sensor measurements to determine whether or not the navigation sensor measurements were obtained during satisfactory wellbore survey conditions. The navigation sensor measurements are evaluated to determine whether or not they meet certain predetermined conditions necessary for obtaining a satisfactory survey. A survey recommendation is automatically generating based on the automatic evaluations performed.

FIELD OF THE INVENTION

Disclosed embodiments relate generally to systems and methods for surveying a subterranean wellbore and particularly to a method for automatically accepting and evaluating a wellbore survey.

BACKGROUND INFORMATION

Wellbore surveying measurements are commonly obtained at some interval while drilling. For example, static surveying measurements may be obtained at 30 to 120 foot intervals when a new pipe stand is added to the drill string. The location at which a static survey is obtained is commonly referred to as a survey station. Dynamic surveying measurements may also be obtained at a much higher frequency while drilling (e.g., at 10 second intervals). Such static and dynamic surveying measurements commonly include borehole inclination and borehole azimuth measurements that describe the current direction of drilling. Borehole inclination is an angular measurement that describes the deviation of the borehole from vertical while borehole azimuth is an angular measurement that describes the deviation of the borehole from a reference direction (e.g., magnetic or true north) in the horizontal plane.

The process of acquiring acceptably accurate surveys generally involves meeting several criteria while making the measurements. For example, specific operations may be completed to ensure that satisfactory conditions exist to minimize potential errors. Moreover, the acquired survey measurements are often analyzed to ensure data quality compliance. In present drilling operations, such activities are conducted manually by various rig personnel. Manual operations can be time consuming and inefficient as well as prone to human errors. Therefore, there is room in the art for improved borehole surveying methods.

SUMMARY

A method for automatically evaluating survey of a subterranean wellbore is disclosed. The method includes receiving downhole navigation sensor measurements and automatically evaluating surface sensor data obtained at substantially the same time as the navigation sensor measurements to determine whether or not the navigation sensor measurements were obtained during satisfactory wellbore survey conditions. The navigation sensor measurements may also be evaluated to determine whether or not they meet certain predetermined conditions necessary for obtaining a satisfactory survey. A survey recommendation is automatically generated based on the automatic evaluations performed.

The disclosed embodiments may provide various technical advantages. For example, the disclosed embodiments provide automated acceptance of wellbore surveys. Such automation enables a survey to be quickly and reliably accepted or rejected based on various predetermined acceptance (or rejection) criteria thereby potentially improving survey quality and saving rig time. The disclosed embodiments may provide a high confidence level in that they automatically evaluate both the state of the drill string (i.e., whether or not it is in a predictable state suitable for acquiring a survey) and the quality of the navigation sensor data.

This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosed subject matter, and advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 depicts an example drilling rig on which disclosed embodiments may be utilized.

FIG. 2 depicts a lower BHA portion of the drill string shown on FIG. 1.

FIG. 3 depicts one disclosed embodiment of a system for automatic wellbore survey acceptance.

FIG. 4 depicts a flow chart of one disclosed method embodiment for obtaining wellbore survey.

DETAILED DESCRIPTION

FIG. 1 depicts a drilling rig 10 suitable for using various method and system embodiments disclosed herein. A semisubmersible drilling platform 12 is positioned over an oil or gas formation (not shown) disposed below the sea floor 16. A subsea conduit 18 extends from deck 20 of platform 12 to a wellhead installation 22. The platform may include a derrick and a hoisting apparatus (also referred to as a block or a traveling block) for raising and lowering a drill string 30, which, as shown, extends into borehole 40 and includes a bottom hole assembly (BHA) 50.

In the depicted embodiment, BHA 50 includes a drill bit 32 and one or more downhole navigation sensors 70. The navigation sensors 70 may be deployed substantially anywhere in the BHA 50, for example, in a measurement while drilling (MWD) tool, a logging while drilling (LWD) tool, a steering tool, a near-bit sensor sub, and the like. The drill string may further include multiple navigation sensors deployed, for example, in a steering tool located near the bit 32 and an MWD tool located well above the bit. A navigation sensor set commonly includes a set of tri-axial (three axis) accelerometers and a set of tri-axial magnetometers as described in more detail below with respect to FIG. 2. However, the disclosed embodiments are not limited in this regard as a navigation sensor set may include alternative accelerometer and/or magnetometer arrangements and may additionally and/or alternatively include gyroscopic sensors. The BHA 50 may further include substantially any other suitable downhole tools such as a downhole drilling motor, a downhole telemetry system, a reaming tool, and the like. The disclosed embodiments are not limited in regards to such other tools.

While not depicted the drilling rig may include a rotary table or a top drive for rotating the drill string 30 (or other components) in the borehole. The rig may further include a swivel that enables the string to rotate while maintaining a fluid tight seal between the interior and exterior of the pipe. During drilling operations mud pumps draw drilling fluid (“mud”) from a tank or pit and pump the mud through the interior of the drill string 30 to the drill bit 32 where it lubricates and cools the bit and carries cuttings to the surface. Such equipment is well known to those of ordinary skill in the art and need not be discussed in further detail herein.

The drilling rig may also include various surface sensors (not illustrated on FIG. 1) for measuring and/or monitoring rig activities. These sensors may include, for example, (i) a hook load sensor for measuring the weight (i.e., the load) of the string on the hoisting apparatus, (ii) a block position sensor for measuring the vertical position and/or velocity of the travelling block (or the top of the pipe stand) in the rig as various components are raised and lowered in the borehole, (iii) a drilling fluid pressure sensor for measuring the pressure of drilling fluid pumped downhole, (iv) a drilling fluid flow-in sensor for measuring the flow rate of drilling fluid into the drill string, and (iv) a surface torque sensor for measuring the torque applied by the top drive or rotary table. Such surface sensors are also well known in the industry and need not be discussed in detail.

It will be understood by those of ordinary skill in the art that the deployment illustrated on FIG. 1 is merely an example. While FIG. 1 depicts a drill bit 32, the disclosed embodiments are not limited in this regard, as surveys may also be acquired on open end drill pipe (e.g., during reaming or other non-drilling operations). It will be further understood that disclosed embodiments are not limited to use with a semisubmersible platform 12 as illustrated on FIG. 1. The disclosed embodiments are equally well suited for use with any kind of subterranean drilling operation, either offshore or onshore.

FIG. 2 depicts the lower BHA portion of drill string 30 including drill bit 32 and navigation sensors 70. As described above with respect to FIG. 1, the navigation sensors 70 may include tri-axial accelerometer and magnetometer sensor sets. Suitable accelerometers and magnetometers may be chosen from among substantially any suitable commercially available devices known in the art. FIG. 2 further includes a diagrammatic representation of the tri-axial accelerometer and tri-axial magnetometer sensor sets. By tri-axial it is meant that each sensor set includes three mutually perpendicular sensors, the accelerometers being designated as A_(x), A_(y), and A_(z) and the magnetometers being designated as B_(x), B_(y), and B_(z). By convention, a right handed system is commonly designated in which the z-axis accelerometer and z-axis magnetometer (A_(z) and B_(z)) are oriented approximately parallel with the borehole as indicated (although disclosed embodiments are of course not limited by such conventions). Each of the accelerometer and magnetometer sets may therefore be considered as determining a plane (the x and y-axes) and a pole (the z-axis along the axis of the BHA). Those of ordinary skill will readily appreciate that navigation sensor sets measure the orientation of the tool axis (which is not generally exactly parallel with the borehole axis) and may require correction (e.g., a sag correction) to obtain a better estimate of the borehole orientation.

FIG. 3 depicts one disclosed embodiment of a system 80 for automatically evaluating a wellbore survey. The system may be implemented at the rig site, for example, on a local computer system 85. The system may include a plurality of rig sensors 82, such as the surface sensors referred to with respect to FIG. 1, for obtaining measurements pertaining to the rig activity. The rig sensors may be in electronic communication with the computer system 85 such that the sensor measurements may be transferred to the computer system where they may be used to evaluate rig activity while obtaining a survey. The system may further include a plurality of downhole sensors 90 such as the navigation sensors 70 referred to with respect to FIG. 1. The downhole sensors 90 may also be in electronic communication with the computer system, for example, via a telemetry link such as wired drill pipe, mud pulse telemetry, electromagnetic telemetry, and the like. The computer system 85 is configured to process data from the rig sensors and the downhole sensors to automatically generate a survey report 95. The survey report 95 may include a survey acceptance along with accepted borehole inclination and borehole azimuth values. Alternatively, the survey report 95 may include a survey rejection along with the corresponding reasons for that rejection.

It will be understood that system 80 is not necessarily located entirely at the rig site. For example, the computer system 85 may be located offsite and may communicate with the rig sensors 82 and the downhole sensors 90 via substantially any known means (e.g., wirelessly or via internet or intranet communication channels). The disclosed embodiments are not limited in these regards. Nor are they limited to any particular hardware implementation of the system 80.

FIG. 4 depicts a flow chart of one disclosed method embodiment 100 for obtaining a wellbore survey. At 102 various operations may be performed in preparation for the survey operation to promote optimal (or satisfactory) wellbore survey conditions. Borehole navigation measurements are acquired at 104. Surface sensor data is evaluated at 106 to verify that satisfactory conditions existed at the time the survey measurements were acquired in 104. The navigation sensor measurements are evaluated at 108 according to certain dynamic criteria to ensure high data quality. Measurement correction processes may be optionally employed at 110 to improve survey quality. At 112 a recommendation (or report) is automatically generated regarding survey quality and subsequent actions such as accepting or rejecting the survey, continuing drilling, obtaining another survey, etc.

As is known to those of ordinary skill in the art, wellbore surveys are commonly obtained at some predetermined interval while drilling the well (e.g. at 30 to 120 foot intervals when adding a new pipe stand to the drill string). Measurement while drilling (MWD) surveys commonly include three-axis accelerometer and three-axis magnetometer measurements from which a borehole inclination and a borehole azimuth may be computed. Borehole inclination is a measure of the deviation of the direction of drilling from vertical while borehole azimuth is a measure of the deviation of the direction of drilling (in the horizontal plane) from magnetic (or true) north. In order to improve survey accuracy, navigation sensor measurements (survey measurements) are commonly made when the sensors are stationary and in the absence of magnetic interference. The disclosed embodiments may be utilized with either static or dynamic surveys.

Preparation operations may be performed at 102 to increase the likelihood that that satisfactory conditions exist when the survey measurements are made. For example, the drill string may be lifted off-bottom thereby enabling torsional and compressional energy in the string to be released. Likewise, the top drive (or rotary table) and block may be held stationary such that the sensors are stationary and free of rotational and axial motion. The pumps may be turned off or turned on depending on the particular rig and BHA configuration.

Navigation sensor measurements (e.g., accelerometer and magnetometer measurements) may be obtained at 104 and transmitted to the surface (e.g., via a conventional telemetry channel). The measurements may be time stamped downhole. Alternatively, a time at which the measurements were made may be directly measured or inferred from various surface measurements. The accelerometer measurements may include tri-axial measurements including A_(x), A_(y), and A_(z) measurements while the magnetometer measurements may also include tri-axial measurements including B_(x), B_(y), and B_(z) measurements as described above with respect to FIG. 2. Alternatively, the accelerometer and magnetometer measurements may be processed downhole to obtain borehole inclination, borehole azimuth, toolface, magnetic dip, total gravitational field, and total magnetic field which may be transmitted to the surface.

The surface sensor data may be automatically evaluated at 106 to verify that satisfactory conditions existed at the time the survey measurements were acquired in 104. For example, the hook load sensor data may be evaluated to ensure that the drill bit was off-bottom at the time the navigational sensor measurements were made (drill bit and hole depths may also be compared to determine if the rig is off-bottom). The block position sensor data may be evaluated to ensure that the block velocity was zero (or near zero). The torque sensor data may be evaluated to ensure that the rotate rate of the drill string was zero (or near zero). Moreover, the drilling fluid pressure sensor data or flow-in sensor data may be evaluated to ensure that the pumps were on or off depending on the rig. The bit and hole depth measurements may also be evaluated to determine the proximity of the navigation sensors to a magnetically hot casing string or casing shoe. The distance between the sensors and magnetically hot casing components is desirably greater than some predetermined threshold.

The accelerometer and magnetometer measurements may be automatically evaluated at 108 to verify that the measurements meet certain predetermined conditions for obtaining a survey of satisfactory quality. For example, the accelerometer measurements may be processed to compute a total acceleration that may be compared with a reference gravitational field to ensure that the total acceleration is equal to the magnitude of the earth's gravitational field (within predetermined limits). Likewise, the magnetometer measurements may be processed to compute a total magnetic field that may be compared with a reference value of the earth's magnetic field to ensure that the total magnetic field is equal to the magnitude of the earth's magnetic field (within predetermined limits). Moreover, the magnetometer measurements may be further processed to compute a magnetic dip angle that may be compared with a reference value at the drilling location to ensure that measured magnetic dip angle is equal to the magnetic dip angle of the earth's gravitational field (within predetermined limits).

The total acceleration may be computed, for example, as follows:

A=√{square root over (A _(x) ² +A _(v) ² +A _(z) ²)}  (1)

where A represents the total acceleration and A_(x), A_(y), and A_(z) represent the x-, y-, and z-axis accelerometer measurements. In the absence of drill string vibrations, the total acceleration should equal the earth's gravitational acceleration. The total magnetic field may be computed, for example, as follows:

B=√{square root over (B _(x) ² +B _(v) ² +B _(z) ²)}  (2)

where B represents the total magnetic field and B_(x), B_(y), and B_(z) represent the x-, y-, and z-axis magnetometer measurements. In the absence of external magnetic interference (e.g., from magnetic drill string components or magnetic ores in the formation), the total magnetic field should equal the earth's magnetic field. The magnetic dip angle may be computed, for example, as follows:

MDip=B _(x) cos(TF)sin(Inc)+B _(y) sin(TF)sin(Inc)+B _(z) cos(Inc)  (3)

where TF represents the toolface angle (high side angle) and Inc represents the borehole inclination. The toolface angle and borehole inclination may be computed from the tri-axial accelerometer measurements, for example, as follows:

$\begin{matrix} {{TF} = {{{arc}\; {\tan \left( \frac{A_{y}}{A_{x}} \right)}} = {{{arc}\; {\cos\left( \frac{A_{x}}{\sqrt{A_{x}^{2} + A_{y}^{2}}} \right)}} = {{arc}\; {\sin\left( \frac{A_{y}}{\sqrt{A_{x}^{2} + A_{y}^{2}}} \right)}}}}} & (4) \\ {{Inc} = {{arc}\; {\tan\left( \frac{\sqrt{A_{x}^{2} + A_{y}^{2}}}{A_{z}} \right)}}} & (5) \end{matrix}$

The evaluation at 108 may alternatively and/or additional include co-processing the total acceleration, the reference value of the earth's gravitational field, the total magnetic field, the reference value of the earth's magnetic field, the magnetic dip angle, and the reference value of the earth's magnetic dip angle to obtain a survey confidence value which may in turn be compared with a reference confidence value. For example, the survey may be accepted when the computed confidence value is greater than or equal to the reference confidence value and rejected when the computed confidence value is less than the reference confidence value.

The reference gravitational field of the earth and the reference magnetic field of the earth (including both the magnitude and direction (or dip)) are commonly known, for example, from previous geological survey data (e.g., as available from the U.S. Geological Survey). However, for some applications it may be advantageous to measure the gravitational and magnetic fields in real time on-site at a location substantially free from magnetic interference, e.g., at the surface of the well or in a previously drilled well. Measurement of the gravitational and magnetic fields in real time may be advantageous in that it may account for time dependent variations (e.g., the earth's magnetic field is known to vary with time). However, at certain sites, such on an offshore drilling rig, it may not be possible to locate a magnetically clean measurement site or site free from external vibrations). In such instances, it may be preferable to utilize previous geological survey data in combination with suitable interpolation and/or mathematical modeling (i.e., computer modeling) routines known in the art.

It will be understood that the evaluation in 108 may be performed downhole by a downhole processor. For example, the total acceleration, the total magnetic field, the magnetic dip angle, and/or or the confidence value may be computed downhole and compared with corresponding reference values stored in downhole memory. In such an embodiment, the navigation sensor measurements may be transmitted to the surface along with an indication of survey acceptance or rejection. Alternatively, navigation sensor measurements may be transmitted to the surface only upon acceptance of the measurements. In such an embodiment, a rejection may trigger the navigation sensors to automatically make new measurements.

It will further be understood that the evaluation in 108 may result in partial acceptance and/or a partial rejection of the navigation sensor data. For example, the quality of the accelerometer data may be acceptable thereby resulting in an acceptable borehole inclination measurement while at the same time the quality of the magnetometer data may unacceptable resulting in an unsatisfactory borehole azimuth measurement.

Measurement correction processes may be optionally employed at 110 to improve survey quality (navigation sensor data quality). Such measurement correction processes may include, for example, sag corrections to correct for misalignment of the drill string with the borehole and multi-station analysis to correct for magnetic interference in the drill string.

A survey recommendation (or report) may be automatically generated at 112. For example, if the evaluations performed at 106 and 108 indicate that the survey is of satisfactory quality, the survey may be automatically accepted and a recommendation for drilling to continue may be given. Alternatively, if one (or both) of the evaluations performed at 106 and 108 indicate that the survey result is questionable, the survey may be rejected and a recommendation for conducting another survey may be given. The reasons for rejection may also be noted to alert rig personnel. For example, the survey may be rejected (or flagged for further review) if one of the rig sensors indicates at 106 that the conditions were not satisfactory at the time the survey measurements were obtained. Alternatively, the survey may be rejected if the survey measurements do not satisfy the above described predetermined conditions (as evaluated in 108).

Automatic acceptance or rejection of dynamic survey data may employ a similar methodology. For example, single axis (z-axis) accelerometer and magnetometer data may be automatically compared with reference obtained from the previous static survey.

Although automatic wellbore survey acceptance and certain advantages thereof have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. 

What is claimed is:
 1. A method for surveying a subterranean wellbore, the method comprising: (a) deploying a drill string in the subterranean wellbore, the drill string including one or more navigation sensor sets; (b) performing survey preparation operations to promote satisfactory wellbore survey conditions based upon a position of the drill string within the wellbore and specific requirements of the navigation sensor sets for taking and communicating a survey; (c) causing the downhole navigation sensor sets to obtain navigation sensor measurements; (d) automatically evaluating surface sensor measurements obtained at substantially the same time as the navigation sensor measurements to determine whether or not the navigation sensor measurements were obtained during satisfactory wellbore survey conditions; (e) automatically evaluating the navigation sensor measurements to determine whether or not the navigation sensor measurements meet certain predetermined conditions necessary for obtaining a satisfactory survey; and (f) automatically generating a survey recommendation based on said automatic evaluations performed in (d) and (e).
 2. The method of claim 1, wherein the survey preparation operations comprise (i) lifting the drill string such that the drill bit is off bottom and (ii) holding the drill string rotationally stationary with respect to the subterranean wellbore.
 3. The method of claim 1, wherein the navigation sensor measurements comprise accelerometer measurements and magnetometer measurements.
 4. The method of claim 1, wherein the surface sensor measurements comprise at least one of hook load sensor measurements, traveling block position and velocity measurements, surface torque and rotation rate measurements of the drill string, and bit and hole depth measurements.
 5. The method of claim 4, wherein the surface sensor measurements verify satisfactory wellbore survey conditions when (i) at least one of the hook load sensor measurements and the bit and hole depth measurements indicate that the drill bit is off-bottom, (ii) the traveling block position and velocity measurements indicate that a velocity of the traveling block is about equal to zero, and (iii) the drill string torque and rotation rate measurements indicate that a rotation rate of the drill string is about equal to zero.
 6. The method of claim 4, wherein the surface sensor measurements verify satisfactory wellbore survey conditions when the bit and hole depth measurements indicate that a distance between the navigation sensors and magnetically hot casing components is greater than a predetermined threshold.
 7. The method of claim 1, wherein said automatic evaluation in (e) comprises at least one of the following: (i) processing the navigation sensor measurements to compute a total acceleration and comparing the total acceleration with a reference value of earth's gravitational field, (ii) processing the navigation sensor measurements to compute a total magnetic field and comparing the total magnetic field with a reference value of the earth's magnetic field, (iii) processing the navigation sensor measurements to compute a magnetic dip angle and comparing the magnetic dip angle with a reference value of earth's magnetic dip angle, (iv) co-processing the total acceleration, the reference value of the earth's gravitational field, the total magnetic field, the reference value of the earth's magnetic field, the magnetic dip angle, and the reference value of the earth's magnetic dip angle to obtain a survey confidence value.
 8. The method of claim 7, wherein the automatic evaluation in (e) verifies that the predetermined conditions were met for obtaining a satisfactory survey when (i) the total acceleration is substantially equal to the reference value of earth's gravitational field, (ii) the total magnetic field is substantially equal to the reference value of the earth's magnetic field, and (iii) the magnetic dip angle is substantially equal to the reference value of earth's magnetic dip angle.
 9. The method of claim 1, wherein the survey recommendation comprises an automatic survey acceptance when the automatic evaluation in (d) verifies that the navigation sensor measurements were obtained during satisfactory wellbore survey conditions and the automatic evaluation in (e) verifies that the navigation sensor measurements meet the predetermined conditions necessary for obtaining a satisfactory survey.
 10. The method of claim 1, further comprising: (g) automatically employing measurement correction processes to improve quality of the navigation sensor measurements.
 11. A method for automatically evaluating a survey of a subterranean wellbore, the method comprising: (a) receiving downhole navigation sensor measurements; (b) receiving surface sensor measurements made at substantially the same time as the navigation sensor measurements; (c) automatically evaluating the surface sensor measurements to determine whether or not the navigation sensor measurements were obtained during satisfactory wellbore survey conditions; (d) automatically evaluating the navigation sensor measurements to determine whether or not the navigation sensor measurements meet certain predetermined conditions necessary for obtaining a satisfactory survey; and (e) automatically generating a survey recommendation based on said automatic evaluations performed in (c) and (d).
 12. The method of claim 11, wherein the navigation sensor measurements comprise tri-axial accelerometer measurements and tri-axial magnetometer measurements.
 13. The method of claim 11, wherein the surface sensor measurements comprise at least one of the following: hook load sensor measurements, traveling block position and velocity measurements, surface torque and rotation rate measurements of the drill string, and bit and hole depth measurements.
 14. The method of claim 13, wherein the surface sensor measurements verify satisfactory wellbore survey conditions when (i) at least one of the hook load sensor measurements and the bit and hole depth measurements indicate that the drill bit is off-bottom, (ii) the traveling block position and velocity measurements indicate that a velocity of the traveling block is about equal to zero, and (iii) the drill string torque and rotation rate measurements indicate that a rotation rate of the drill string is about equal to zero.
 15. The method of claim 13, wherein the surface sensor measurements verify satisfactory wellbore survey conditions when the bit and hole depth measurements indicate that a distance between the navigation sensors and magnetically hot casing components is greater than a predetermined threshold.
 16. The method of claim 11, wherein said automatic evaluation in (c) comprises at least one of the following: (i) processing the navigation sensor measurements to compute a total acceleration and comparing the total acceleration with a reference value of earth's gravitational field, (ii) processing the navigation sensor measurements to compute a total magnetic field and comparing the total magnetic field with a reference value of the earth's magnetic field, and (iii) processing the navigation sensor measurements to compute a magnetic dip angle and comparing the magnetic dip angle with a reference value of earth's magnetic dip angle.
 17. The method of claim 16, wherein the automatic evaluation in (c) verifies that the predetermined conditions were met for obtaining a satisfactory survey when (i) the total acceleration is substantially equal to the reference value of earth's gravitational field, (ii) the total magnetic field is substantially equal to the reference value of the earth's magnetic field, and (iii) the magnetic dip angle is substantially equal to the reference value of earth's magnetic dip angle.
 18. The method of claim 11, wherein the survey recommendation comprises an automatic survey acceptance when the automatic evaluation in (b) verifies that the navigation sensor measurements were obtained during satisfactory wellbore survey conditions and the automatic evaluation in (c) verifies that the navigation sensor measurements meet the predetermined conditions necessary for obtaining a satisfactory survey.
 19. The method of claim 1, further comprising: (e) automatically employing measurement correction processes to improve quality of the navigation sensor measurements.
 20. A system for automatically evaluating a wellbore survey, the system comprising: a plurality of surface sensors deployed on a drilling rig; a computer processor in electronic communication with the surface sensors, the processor configured to automatically (a) receiving downhole navigation sensor measurements, (b) receive sensor measurements from the surface sensors; (c) evaluate the surface sensor measurements to determine whether or not the navigation sensor measurements were obtained during satisfactory wellbore survey conditions; (d) evaluate the navigation sensor measurements to determine whether or not they meet certain predetermined conditions necessary for obtaining a satisfactory survey, and (e) generate a survey recommendation based on said automatic evaluations performed in (c) and (d). 